Method for producing a wire cable and use of said method

ABSTRACT

The invention relates to a wire cable ( 12 ) which is produced by producing the wires already in the cable configuration by layer construction. Preferably, the wires are already formed onto terminal couplings. The wire cable ( 12 ) so produced is suitable for specific purposes only. It is advantageous in that it is not influenced by variations in quality of the starting product or by variations in manufacturing parameters. The inventive wire cable ( 12 ) is used for applications where short cables are required and where their absolute regularity can be made use of. An important field of application of the inventive method is the production of samples for obtaining background data required for optimizing wire cable construction. According to the inventive method, samples of identical basic cable structure but different wire diameters and/or lay lengths of strands, a core wire and/or the cable are produced and the characteristic features of interest are determined. In the tests, different absolute values are found. However, the values in relation to each other show influences of geometry, i.e. wire diameters and lay length modifications. A comparison with samples produced according to conventional manufacturing methods can be used to find correctional variables which can be taken into consideration when required.

The invention relates to a method for producing a wire rope.

Furthermore the invention relates to an application of such a method.

The invention has the object to design a wire rope with new properties.

According to the invention, this object is met in that the wires arealready made in the rope configuration by means of layer composition.

The wire rope created in this way does not have the tensile strength ofa normal wire rope. It is only used for special purposes. Its advantagelies in that fact that it is neither influenced by quality fluctuationsof the primary material nor by fluctuations of the productionparameters. The wire rope may be deployed in cases where its absoluteevenness can be exploited.

The normal wire ropes are subject to fluctuations in material and in thediameter of the wires as well as fluctuations of a great number ofproduction parameters ranging from the wires, to the strands, and to therope, where applicable, the core rope and terminal rope.

The wires can come from different steel charges and furthermore fromother reduction steps with various cross-section reductions and thushave or incur various compositions, initial strengths, longitudinalstretching and increases in strength.

As a result of fluctuations in machine settings, such as preforming,spooling deceleration, straightening roller settings and reversedrotation both during the strand production and, where applicable, themulti-stage rope production, differing properties pertaining todiameter, elongation, twisting and torque performance as well asinternal stresses, can have arisen to a non-negligible degree across theentire length of the wire rope.

During the production of samples for the development of the rope, oneaims to at least use wires from the same producer. However, even in thiscase there are occasionally variations. Over the course of productionthe manufacturer may be switched repeatedly which can again lead tofurther changes in the wire rope.

In cases in which only short wire ropes are required and uniformity is adecisive factor, the wire ropes according to the invention thus have anadvantage.

The most significant advantage results from the design that the wiresare respectively molded directly to the coupling pieces located at theend of the wire rope.

The normal wire ropes are furnished with press sleeves or fanned out andfused. The discontinuity of the rope structure at these places has aneffect far into the wire rope. Short ropes are therefore particularlyirregular, while the sockets made by the hand at the ends lead toadditional unavoidable inaccuracies and their related effects.

If, for example, several short wire ropes must interact absolutelyevenly, for instance for control purposes in astronautics, the wireropes according to the invention with molded coupling pieces arepositively an advantage in spite of high production costs.

The production of samples for obtaining raw data for an optimization ofa wire rope design is an important application area of the methodaccording to the invention, wherein samples of a core rope and/or ropehaving an essentially identical rope structure, however different wirediameter and/or lay lengths of the strands are made and the propertiesof interest can be ascertained.

In order to find, for example, the best lay length for the core rope andthe best lay length for the rope, i.e. the subsequent stranded outerstrand position, for a multi-layer wire rope, a number of sample ropeswith different core rope lay lengths and different rope lay lengths aremade.

Five to nine samples, for example, are then cut with lengths of 1 to 20m, in order to determine the E-modulus, breaking strength andoverstraining in a pull test; further common tests include the torquetest, the rotation angle test, the flexibility test, the bending stresstest and the pulsating tensile stress test.

An otherwise desirable larger number of variations is not possible dueto the size of the costs.

The costs, as already mentioned above, are again increased by means ofthe interference of the rope interconnection in the end areas of thesample ropes.

Based on the method according to the invention, the samples can be madein the shape of one-piece test pieces, in which the wires arerespectively molded directly to the coupling pieces located at the ends.

The test pieces made in this way having a length of for example only 10to 20 cm and the metal structure and surface of the wires, cannothowever be equated with the samples of wire ropes which are made bymeans of stranding pulled wires. Different absolute values are found inthe tests.

In relation to the values, however, the influences of geometry, i.e. ofthe wire diameter and of the lay length changes, can also be identifiedherein. A comparison of values found in samples made according tocustomary mode of production, can reveal, for example, correction valueswhich could be taken into account.

The test pieces can be utilized in combination with a correspondinglyreduced number of common rope samples for an optimization problem.

The small length of the test pieces is not a disadvantage. In allmentioned tests with the exception of the bending stress test, thelength of the sample either had no impact or an impact which iscomputable.

The advantages achieved on the other hand are considerable.

The measurement results for conventional test ropes not only depend onthe change of the rope parameters, but they are also superimposed by theabove mentioned variances from production. As generally known, this canlead to big errors given an unfavorable concurrence of events. Incontrast, the differences in measurement results can almost entirely beattributed to parameter changes using the uniform test pieces accordingto the invention.

The problem of wire availability and diameter tolerances which isassociated with the conventional production of test ropes is completelyomitted.

The interference of the rope structure at both the ends is only minimaland largely negligible. The wires are not bent a priori at the end bythe holder or deformed in their cross section. They merge into thecoupling piece on their entire cross section in the same material.

The already mentioned advantages, however, would likewise apply to testpieces made according to the invention without the molded couplingpieces.

According to a further embodiment of the invention, the composition ofthe wires is started in a wire position relative to each other whichcorresponds to or approximates the contact pressure of the wires ontoeach other under load of the wire rope, and the wires are fanned out ona subsequent short section to such an extent that they can then be builtup separately from each other if necessary. At the end the processproceeds accordingly.

In this way a small discontinuity of the rope structure at the ends,possibly even occurring according to the invention, is mitigated and itsimpact into the length of the wire rope is shortened:

The wires built separately from each other press against each otherunder load on their length, however are kept at the original distance atthe ends. This distance is larger without the preceding measure, so thata fanning out of the wires toward the end results.

The proposed reversed fanning out closes, on the other hand, under loadand a slight bending of the wires, and the rope geometry remainsconstant to the end.

Inasmuch as interference from the bending of the wires is detected, itis possible to implement the measure only to a limited extent and stillfind an advantageous compromise between the corresponding bending of thewires and the fanning out of the wires toward the end.

Analogously, the composition of the wires can be started at an angle ofthe wires to the cross sectional plane of the wire rope, which is equalto or approximates the angle when loading the wire rope; the wires arethen deflected at that angle which is designed to be without load.

The mentioned position of the wires relative to each other whichcorresponds to the contact pressure means that the wires are joinedtogether in that position. The wire rope thereby receives cohesion, evenif the wires are not molded to coupling pieces.

In a position at a distance from each other, the wire ends could beconnected by means of webs that are built up between them.

Coupling pieces could also be welded or molded, if necessary also glued,to such ends of a wire rope.

On the one hand, one will generally aim to keep the test piece as shortas possible, so that the aspect ratios (wire diameter to height) for thelayer structure do not get too high. On the other hand, the test piecesshould after all have a length of at least the biggest lay length of astrand, a core rope or of a rope contained in the test pieces, so that arope-characteristic performance is achieved.

The slender wire ropes allow, according to a further embodiment of theinvention, for a number, preferably a multitude of wire ropes to beproduced in the same work step.

However, this not only implies the obvious rationalization associatedtherewith. Production variances resulting from deviations betweendifferent work steps are additionally eliminated, which again, in thiscase however, only occur to a very minor extent.

The material cannot be comparable to that of real wires. The usuallypresent metallurgic possibilities do not exist; the textures created bymilling and pulling of the wires can be reproduced.

According to the material applications known within the scope ofselective laser meltings, a single component material, and thereforesteel, however, can be selected, and the steel powder can be completelymelted on locally by means of a laser beam, so that the material of theproduced wires essentially presents a continuum. Approximately half ofthe tensile strength of normal wires is achieved.

If necessary the test piece can still undergo metallurgic heattreatments as a whole.

Titanium may also be considered as a material.

The wire rope could also only comprise a single strand.

The technique of the layer composition is known in several variations. Arepetitive process cycle comprising 3 steps is the common principle.First, a vertically traveling building platform is lowered by the amountwhich is predetermined by the layer thickness. Then, a material layer,for example, powder is applied such that the preceding layer iscompletely covered at the hardened places as well as at places which arenot hardened. In a final step the component data of the most recentlayer provided in a 3D CAD is transferred to the material by means ofenergy radiation, in order to harden it in places. The steps arerepeated until the component is built. Several systems are known whichdiffer in the materials to be processed, the energy source, and inadditional process steps.

Selective laser melting is applied for producing identical prototypes inbatches, inserts with contour-fitted cooling ducts for tool and moldmaking as well as for other components with a hollow structure; andfurthermore, single components such as medical individual implants andsmall batches.

In contrast, neither parts usable in a standard way nor parts which areexactly identical in form to such parts are made by applying the methodaccording to the invention.

The test pieces are entities of their own which are only designed andusable for determining the property values in correlation with certaingeometries, wherein these results can not yet be used directly and onlylead to construction data which is of practical use after consideringsimilarity correlations.

The invention is illustrated in the drawings which are described indetail as follows:

FIG. 1 shows a device for carrying out selective laser melting in avertical section,

FIG. 2 shows a cross section of a wire rope.

A raisable and lowerable platform 2 is arranged as a base in a duct 1,so that a chamber 3 having a variable depth is formed. The chamber 3merges at its top side into a process chamber 4 having a greater crosssection. A powder application device 5 located in the process chamber 3which is filled with a protective gas is movable above the length ofchamber 3. The powder application device 5 itself is to be filled bymeans of a feeding device 6 connected to a storage container.

A laser beam source 9 with a control device for the laser beam 10 whichis steered from a CAD system onto the X-Y coordinate is arranged over afixture 8 of the process chamber 4 which is equipped with a couplingwindow 7.

In the chamber 3, three wire ropes 12 which are in the process of beingbuilt, extend at the height of the chamber in a metal powder pour 11.

The cross section of the wire rope 12 is shown on a larger scale in FIG.2.

The powder application device 5 moves above the chamber 3 and evenlyapplies a layer with a thickness of, for example, 20μ over the metalpowder pour 11 and the wire cross sections.

The metal powder for example consists of tool steel 1.2343, high-gradesteel 1.4404 or steel 42 TrMo4. It has a grain size of <45μ, but couldalso be even finer.

After the first layer is laid the laser beam, for example, with a chartspeed of 100 mm/sec is guided on parallel paths over the metal powderpour 11 and the metal powder layer resting on the wire. It is, however,only activated on those cross section sections in which the wires are tobe built. The appropriate geometry data is provided in the shape of a 3DCAD model in the CAD system. The CAD model is dissected by means ofspecial software into layers with the appropriate layer thickness. Thelaser beam source and the control of the laser beam are steeredaccordingly.

The laser beam has an effectiveness of, for example, a diameter of 200μin its surrounding area. Accordingly, the mentioned % paths are locatednext to each other at a distance of 100μ. The effective depth of thelaser beam is approximately equal to the layer thickness, i.e., forexample, 20μ.

At the borders of the wire cross sections the activating of the laserbeam source is delayed and the turning off is accelerated according tothe effectiveness diameter of the laser beam in order to exactly producea wire diameter of, for example, 1.5 to 2 mm.

After extracting the finished wire ropes 12, the metal powder located intheir hollow spaces is removed by shaking, knocking, blowing, washingand/or the like is removed down to minor residue.

For this purpose, the short wire rope can also be expanded slightly inthe elastic deformation area by twisting and/or compression. These canbe alternately expanded slightly where lay directions are in oppositionto each other in different cross section areas by tightening the otherarea more intensely.

Axial outlet ducts may be recessed at least in the extension of thestrand gusset areas in molded coupling pieces.

1. A method for producing a wire rope, wherein the wires are alreadymade in the rope configuration by means of layer composition.
 2. Themethod according to claim 1, wherein the layers are produced which restdiagonally to the extension direction of the wires.
 3. The methodaccording to claim 1, wherein the wires, preferably of steel ortitanium, are made by means of selective laser melting.
 4. The methodaccording to claim 1, wherein the wires are respectively molded directlyto the coupling pieces located at the end of the wire rope.
 5. Themethod according to claim 1, wherein the composition of the wires isstarted in a wire position relative to each other which corresponds toor approximates the contact pressure of the wires onto each other underload of the wire rope, and the wires are fanned out on a subsequentshort section to such an extent that they can then be built upseparately from each other.
 6. The method according to claim 1, whereinthe composition of the wires can be started at an angle of the wires tothe cross sectional plane of the wire rope, which is equal to orapproximates the angle when loading the wire rope, and the wires arethen deflected at that angle which is designed to be without load. 7.The method according to claim 5, wherein the composition of the wires atthe end corresponds.
 8. The method according to claim 4, wherein thecoupling pieces have outlet ducts are recessed in an extension of thestrand gusset areas for non-fixed metal powder.
 9. The method accordingto claim 1, wherein the entire wire rope is heat treated.
 10. The methodaccording to claim 1, wherein a plurality of wire ropes is produced inthe same work step.
 11. Use of the method of claim 1 for producingsamples for obtaining raw data for optimizing construction of a wirerope, wherein samples of a core rope and/or rope having an identicalrope structure, however different wire diameter and/or lay lengths ofthe strands are made and the properties of interest can be ascertained.12. The method according to claim 11, wherein the samples have a lengthof at least the largest lay length of a strand, a core rope or of a ropecontained in the samples.